Lateral metal oxide semiconductor field effect transistors are a unique class of three terminal transistor devices which include source, drain and gate electrode terminals wherein the electric fields sustained between the source and drain is distributed laterally. In silicon-based semiconductor materials, a variant of LMOSFETs known as laterally diffused metal oxide semiconductor field effect transistors (LDMOSFETs) are typically manufactured—the advantages of which include cost-efficacy, and performance advantages around a low defect interface between silicon and silicon dioxide and/or other “high—K” dielectric materials such as hafnium oxide which are materials suspended between the semiconductor and the gate electrode and employed to achieve the transistor field effect. However, silicon based LDMOSFETs have fundamental limits centered on the low critical field of the material defined as the electric field beyond which the material breaks down and losses its semiconductor properties—a direct consequence of the relatively low energy band gap of the material of 1.14 eV; its low switching frequency of below 100 kHz; its high on-resistance of above 200 mΩ-cm−2; and its low operating temperatures of about 150° C.
Furthermore, the utility of hybrid hetero-structures comprising of AlInGaN based materials deposited directly onto silicon substrates have costs and performance benefits. The cost benefits arising from the economies of scale stemming from the availability of large surface area silicon substrates—which is historically the most affordable semiconductor substrates as well as well the fully amortized cost of silicon processing equipment. The performance benefits arising from the availability of a two dimensional electron gas (2DEG) at the interfaces of AlInGaN layers semiconductor layers leading to performance benefits such as ultra-low impedances or On-Resistances. However, the defectivity pertinent to these hybrid materials i.e. above 106 cm−2 dislocation densities has been posited as a preeminent factor in lower field and voltage rating as well as a contributor to the deleterious density of surface states in AlInGaN/GaN based hybrid materials on silicon based transistors. Moreover, the utility of lower energy gap substrate materials such as silicon can lead to pre-mature breakdown even for AlInGaN/GaN MOSFETs as depletions regions in the off-state may extend into the lower critical field silicon substrate.
Nonetheless, these hybrid materials on silicon have enabled a generation of devices including AlGaN based High Electron Mobility Transistors (HEMTs) and “normally-on” field effect transistors utilizing Schottky gates. Whereas significant effort has been invested in the commercialization of AlGaN based LMO(I)SFETs, the realization of devices which have critical field ratings at about the theoretical field strength of AlInGaN based devices and voltage ratings exceeding breakdown voltages of 800V remains technically challenging and elusive.
A process which enables the placement of high quality AlInGaN based materials i.e with dislocation densities below about 107 cm−2 on substrate materials with comparable energy band gap and critical breakdown field strength in conjunction with large surface areas of at least about 50 mm diameter and which relocates the current conducting channel away from orthogonally propagating line and or area defects such as in devices in which the current conducting channel is rotated to occur in the plane of a sidewall of the semiconductor would effectively allow the realization of AlInGaN based transistors which can function at approximately the theoretical critical field anticipated for AlInGaN based materials, at a voltage rating between 800V to 15,000V as well as by pass the deleterious surface state effects of line defects terminating at the nominal planar lateral surface of the semiconductor; and at a levelized cost structure approximately similar to silicon based devices.
Whereas the advent of silicon carbide (SiC) based devices has extended the functionality of power MO(I)SFETs to higher electric fields and thus higher operating voltages of up to 10 kV—essentially due to the higher band gap of the material of 3.0 eV; vertical MOSFET architecture; higher switching frequencies; and higher operating temperatures of about 230° C.; SiC based power transistors are still very expensive and with levelized cost of 50 to 100 times those of their silicon counterparts thus limiting their market adoption; the on-Resistances of SiC based transistors at operating temperatures of interests i.e. above 100° C. are markedly higher i.e about 10-100 times those anticipated for AlInGaN based power transistors as a result of the absence of the high channel mobility in AlInGaN based devices due to the sustained two dimensional electron gas (2DEG) typically formed at the interfaces of AlGaInN semiconductor layers.